1. Field of the Invention
The present invention relates to a lens apparatus for adjusting focus or zooming through movement of an optical element in an optical axis direction thereof. In particular, the present invention relates to a lens apparatus having a function of adjusting a light amount through rotation of an operating member arranged on an outer circumferential portion of the lens apparatus, and to an image pickup apparatus including the lens apparatus.
2. Description of the Related Art
According to the related art, there is known a lens apparatus in which an operating member arranged on an outer circumferential portion of the lens apparatus and a movable stop arranged in the lens apparatus for changing an aperture diameter are mechanically interlocked and the light amount is adjusted through manual rotation of the operating member. In this lens apparatus, the operating member on the outer circumferential portion and the movable stop are usually arranged close to each other in an optical axis direction of the lens apparatus. However, due to a positional restriction of the operating member and a restriction on optical design of a position of the stop, the operating member and the movable stop may be arranged across an optical element that moves in the optical axis direction for adjusting focus or zooming. In this case, it is necessary to provide a structure for transmitting a rotational drive force in the lens apparatus.
As a method of transmitting the rotational drive force in the lens apparatus so as to change the aperture diameter of the movable stop, Japanese Patent Application Laid-Open No. H08-86947 discloses a structure transmitting the rotational drive force by a lever member inserted through a cutout formed in a part of a lens barrel that moves in the optical axis direction. In addition, Japanese Patent Application Laid-Open No. 2012-53271 discloses a method of transmitting the rotational drive force by a stop control member including multiple long rod-like members and ring-like members fixed to both ends of the rod-like member.
However, when the rotational drive force is transmitted by the long-arm lever member as in Japanese Patent Application Laid-Open No. H08-86947, a delay of aperture diameter change with respect to an operation amount of the operating member or an untraceable operation range thereof may be generated because of a tip vibration of the lever member due to a distortion of the lever member or a movable portion backlash. In addition, there is another problem in that a difference in aperture diameter between forward and backward movements occurs when forward and backward rotation is performed.
On the other hand, as described in Japanese Patent Application Laid-Open No. 2012-53271, when using the transmitting member in which the two ring members arranged on front and rear sides are connected through multiple rod-like members, the above-mentioned distortion and vibration are suppressed, but there is a problem in that the number of components is large. When the number of components of the transmitting member is large, dimensional errors of the components and assembly variations are accumulated. Therefore, there are problems in that a stop indicator engraved on the operating member and the aperture diameter cannot match with each other at high accuracy, and that an assembly procedure becomes complicated.